Indian Electricity Grid Code
Contents
1.
2.
3.
4.
5.
6.
7.
General
Role of various organisations and their linkages
Planning code for Inter State Transmission
Connection Code
Operating Code
Scheduling and Despatch Code
Miscellaneous
2
1. General
Introduction
IEGC
Rules
Guidelines
Standards
for
Utilities
To plan, develop, operate &
maintain
National/Regional
Grid
Power System
ISTS
connected with / using
• Documentation of the principles
which define relationship
between various users
•Facilitation of optimal operation
•Facilitation
power
markets and ancillary services
4
• Facilitation
renewable energy sources
Compliance Oversight (1.5)
RLDC
Report
Repeated
Violation/
Persistent
Non
Compliance
RPC
suo-motto
CERC
Action
Consensus
Report issues
not sorted
5
Compliance Oversight (1.5)
Non Compliance
by
NLDC,
RLDC,
SLDC,
RPC
or any other person
Report
by any
person
through
petition
CERC
Action
6
2. Role of
Various Organizations and their
linkages
NLDC, RLDC, RPC, CTU, CEA,
SLDC & STU
Role of NLDC (2.2)
NLDC
•
•
•
•
•
•
•
•
Economy and Efficiency of National Grid
Monitoring of operations and grid security of National Grid
Restoration of synchronous operation of National Grid
Trans-national exchange of power
Feedback to CEA & CTU for national Grid Planning
Dissemination of information
Levy and collection of fee and charges - CERC
Disse
Supervision
Coordinate
Supervision & control
RLDC
Coordinate
Inter Regional Links
Accounting
RPC for
regional outage Plan
8
Role of RLDC (2.3)
RLDC
Exclusive
functions
• Real time operation , control & contingency
analysis
• Generation scheduling/ re-scheduling
• Restoration
• Metering & data collection
• Compiling & furnishing of operation data
• Operation of Regional UI pool Account. Reactive
energy account and Congestion charge account
• Operation of ancillary services
9
Role of RLDC (2.3)
RLDC
Apex body
for
integrated
operation
Comply
the
directions
Directions
Central
For ST
Open
AccessNodal
Agency
SLDC
State
• Licensee
• Generating company
• Generating station / Substations
• any other concerned person
Functions
•optimum scheduling
and despatch of
electricity
•Monitor grid operation
•Keep accounts of
electricity transmitted
• Exercise Supervision
and control over
the ISTS
• Real time operations
10
Role of RPC (2.4 )
RPC
• Facilitate the stable and smooth operations of the system
• Functions:
– regional level operation analysis
– facilitate inter-state/inter-regional transfer of power
– facilitate planning of inter-state/intrastate transmission system
– coordinate maintenance of generating units
– coordinate maintenance of transmission system
– protection studies
– Planning for maintaining proper voltages
– Consensus on issues related to economy and efficiency
MS SRPC shall certify Availability
of transmission system
Prepare Regional Energy Account,
Weekly UI, Reactive & Congestion
charge account
Decisions
RLDC/SLDC/CTU/
11
STU/ Users
Role of CTU (2.5)
CTU
•
to undertake
transmission of
electricity through
ISTS
Planning
RLDC
• to ensure development
of an efficient, coordinated and
economical ISTS
State1
shall operate
STU
ISTS lines
CTU/to provide non-discriminatory Open Access
– Will not engage in trading and generation
– For LTOA & MTOA nodal agency
Central
Govt.
State Govt.
RPC
Generating
State2 Companies
CEA
Licensees
12
Role of CEA (2.6)
CEA
(Central Electricity Authority)
• will formulate short-term and perspective plans for transmission system
•specify technical standards for construction of electrical plants, electric lines and
connectivity to the grid
•specify safety requirements for construction, operation and maintenance of
electrical plants and electrical lines
•specify grid standards for operation and maintenance of transmission lines
•specify conditions for SEMs
•Promote and assist timely completion of schemes
•To collect and record electrical data- cost, efficiency
•To carry out investigation ( Electrical system)
• Shall Prepare National Electricity Plan (NEP)
13
Role of SLDC (2.6)
SLDC – Apex body in a State
• Optimum scheduling and despatch
Ensure
compliance
• Monitor grid operations
Directions and
• Keep accounts of electricity
exercise
transmitted
supervision and
• Activities of
control
Licensee,
Real-time operation
generating company,
• exercise supervision and control
generating station,
sub-station
Power System
and any other
concerned person
Directions
State
RLDC
14
Role of STU (2.8)
STU
•
to undertake
transmission of
electricity through
intra-state transmission
system
• to ensure development
of an efficient, coordinated and
economical intra-state
transmission system
Planning
shall operate
SLDC
CTU
State Govt.
Intra-state transmission system
RPC
STU/to provide non-discriminatory Open Access
CEA
Generating
Companies
Licensees
15
Role of STU (2.8)
STU
• Energy transfer
• Efficient
• Economical
• Planning
• Coordination
shall operate
SLDC
Provide non-discriminatory
open access
Intra-state transmission system
• CTU
•State Government
•Generartors
•RPCs
•CEA
•Licencees
16
3. Planning Code for
Inter-state Transmission
• Introduction
• Objective
• Scope
• Planning Philosophy
• Planning Criterion
• Planning Data
• Implementation of Transmission Plan
Introduction
Intra-State
Inter-state
STU
CTU
Transmission schemes
for planning and
coordination
Intra-State
STU
Transmission schemes
for planning and
coordination
CEA
18
Scope of planning code (3.3)
Connected to/using/developing ISTS
CTU
ISGS
GC
ISTS
SEBs
STU
Licensees
IPP
Generation/Transmission of
energy to/from ISTS
Objective
• specify principles,
• specify procedures
•specify criteria
•promote coordination19
•information exchange
Planning Philosophy (3.4)
Long-term plan (10-15 years)
CEA
• inter/intra state transmission system
• continuously updated to reflect
load projections and generation scenarios
• NEP
• Avoid congestion
Annual plan (5 year forward term)
CTU
•
Identification of major
inter state/regional lines including
system strengthening schemes
• Planning schemes shall also consider:
CEA’s:
 Long-term perspective plan
 Electric Power Survey of India report
 Transmission Planning Criteria and
guidelines
 RPC Feedback
 NLDC/RLDC/SLDC feedback
 CERC Regulations
 Renewable capacity addition (MNRES)
20
Planning philosophy (contd...)
• System strengthening schemes by CTU:
– shall be done in consultation with CEA’s
Standing Committee for Transmission System Planning:
• Planning
– On the basis of PPA
– No PPA/ no consensus – CTU may approach CERC in
accordance with CERC (Grant of Regulatory approval
for Capital Investment to CTU for execution of ISTS)
• Planning data:
– submission by STUs/Users to CTU:
21
Planning philosophy (contd...)
•
Voltage management by:
–
–
•
•
•
capacitors, reactors, SVC and FACTs
similar exercise by STU
STU shall plan to evacuate power from ISTS
ISTS & intra-state transmission systems are
complementary & interdependent
If LTA Applications require strengthening of
intra-state transmission system – applicant shall
coordinate with STU
22
Planning Criterion (3.5)
Planning criterion ISTS’s security philosophyCEA guidelines
a) Without load shedding or rescheduling of generation, ISTS shall
withstand and secure against the following outages:
– a 132 KV D/C line, a 220 KV /DC line,
– a 400 KV S/C line, 765 KV S/C line
– single Inter-Connecting Transformer (ICT )
– one pole of HVDC Bi-pole
– Outage of 765 kV S/C line
Without load shedding but could be with rescheduling of generation,
ISTS shall withstand and secure against the following outages:
– a 400 KV D/C line
– a 400 KV S/C line with TCSC
– both pole of HVDC Bi-pole line
– Outage of 765 KV S/C line with series compensation
23
Planning Criterion (3.5)
b) ISTS shall withstand the loss of most
severe single system infeed without loss of
stability
c) Any one of the events defined above should
not cause:
– loss of supply
– prolonged operation of frequency below and
above limits
– unacceptable high or low voltage
– system instability
– unacceptable overloading of ISTS elements
24
Planning Data & Implementation
d)All S/S (132 kV & above) shall have at least two
transformers
e)CTU will carry out reactive power compensation
requirement of ISTS & at ISGS’ switchyard
f)SPS may be planned by NLDC/RLDC in
consultation with CEA, CTU, RPC & Regional
entities – for enhancing transfer capability or to
take care of additional contingencies
25
Planning Data & Implementation
• Planning Data (3.6)
– As per CERC (Grant of Connectivity, LTA and MTOA
in ISTS and related matters) Regulations 2009
• Implementation of Transmission Plan (3.7)
– Actual program of implementation of transmission
lines, ICTs, reactors/capacitors and other transmission
elements as per CERC (Grant of Connectivity, LTA
and MTOA in ISTS and related matters) Regulations
2009
26
4. Connection Code
OBJECTIVE
Comply with
CEA( Technical
Standards for
connectivity to
the Grid) 2007
Minimum
technical &
design criteria
SCOPE
CTU
• Ensure the safe operation,
integrity and reliability of the
grid
•Non-discriminatory
•New/modified connection not
suffer or impose unacceptable
effects
•In advance knowledge about
Connectivity
STU
ISTS
Users connected to ISTS or seeking connection to ISTS
Procedure for connection (4.4)
• User seeking new/modified connection:
– Shall submit an application on standard format
in accordance with CERC (Grant of
Connectivity, LTA and MTOA in ISTS and
related matters) Regulations 2009
– CTU shall process as per above regulations
28
4.5 Connection Agreement
–Connection agreement would
be signed by the applicant in
accordance with CERC (Grant
of Connectivity, LTA and
MTOA in ISTS and related
matters) Regulations 2009
29
Reactive Power Compensation 4.6.1
– by /STUs and Users in the low voltage systems
close to the load points therby avoiding
exchange of reactive power to/ from the ISTS
– Already connected shall provide additional
reactive compensation as per the quantum and
time frame decided by the RPC in consultation
with RLDC.
– Installation and healthiness would be monitored
by RPC
30
Data and Communication Facilities (4.6.2)
– reliable and efficient speech and
communication system to be provided
– Users/STU/CTU shall provide systems to
telemeter power system parameters
•
•
•
•
Flow
Voltage
Status of switches
Status of transformer taps
– Associated communication system to facilitate
data flow up to appropriate data collection point
on CTU’s system as specified by CTU in the
Connection Agreement
31
System Recording Instruments (4.6.3)
– Data Acquisition System/Disturbance
Recorder/Event Logging facilties/Fault Locator
(including time synchronization equipment )
shall be provided and always kept in working
condition
Responsibility for safety (4.6.4)
– CEA (Technical Standards for connectivity to the Grid),
Regulations 2007
– CERC (Grant of Connectivity, LTA and MTOA in ISTS
and related matters) Regulations 2009
– CEA (Safety Requirements for construction, operation
and maintenance of electrical and electric lines)
Regulations, 2008
32
International Connections to ISTS (4.7)
– By CTU in consultation with CEA and MOP
Schedule of assets of Regional Grid (4.8)
– CTU and other transmission licensees shall
submit by 30th Sep a schedule of transmission
assets as on 31st March indicating ownership
on which RLDC has operational control and
responsibility.
33
5. Operating Code
34
Operating philosophy (5.1)
• objective of the integrated operation:
– enhance overall operational reliability and economy
– Cooperate and adopt Good Utility Practice
• NLDC:
– overall operation of National/Inter-Regional Grid
– develop/maintain detailed internal operating procedures
for national grid
• RLDC:
– overall operation of Regional Grid
– develop/maintain detailed internal operating procedures
for regional grid
35
Operating philosophy (5.1)
• SLDC:
– develop/maintain detailed internal operating procedures
for State grid
• All licensee, generating company, generating
station and any other concerned person:
– comply with directions of RLDC/SLDC
e) round-the clock manning by qualified and trained
personnel of:
– control rooms of NLDC, RLDC, SLDC, Power Plant,
Sub Stations (132 kV & above)
– control centres of all regional constituents
36
System Security Aspects (5.2)
•
Synchronism:
– all Users, CTU & STU
– operate their power systems/stations in an integrated
manner
•
No deliberate isolation of part of the grid:
–
–
–
–
except under emergency
safety of human/equipment
when instructed by RLDC
restoration to be supervised by RLDC in coordination
with NLDC/SLDC
37
System Security Aspects (5.2)
•
Important elements list at RLDC:
– not removed without RLDC’s consent or prior consent
– when specifically instructed
– list of important elements to be prepared and shall be
put on website of NLDC/RLDC/SLDC
– emergency removal intimated to RLDC
– tripping, reason, likely time of restoration intimated to
RLDC say within 10 minutes
– Important elements tripping to be informed to NLDC
by RLDC
– Prolonged outage ------ sub-optimal operation---monitored by RLDC------report to RPC-------- finalise
action plan for restoration
38
Restricted Governor Action (5.2(f))
•
•
•
•
Thermal generating > 200 MW and hydro units > 10 MW
on RGMO wef 01.08.2010
Gas Units, Combined Cycle, wind, solar & nuclear
exempted till CERC reviews
When frequency stabilise at 50.0 Hz FGMO would be
intoduced
RGMO
–
–
–
–
–
–
For Frequency < 50.2 Hz no reduction in generation when frequency
rises
Any fall in frequency generation should increase by 5% limited to 105%
of MCR (thermal), 110% MCR (Hydro)
After increase in generation, the unit mey ramp back to original level at
a rate of 1% per minute
At Frequency < 49.7 Hz ramp up could be at higher rate
governors: 3% - 6% droop
any exception: reason & duration to RLDC
39
System Security Aspects 5.2 (s)
Voltage- (kV rms)
Nominal
Maximum
Minimum
765
800
728
400
420
380
220
245
198
132
145
122
110
121
99
66
33
72
36
60
30
40
DEMAND ESTIMATION FOR
OPERARTIONAL PURPOSES
Daily
/Weekly
/Monthly
Wind
Energy
Forecast
Inform to
RLDC/
RPC
ATC/
TTC
Demand Estimation –
Active and reactive
power
on-line estimation
for daily operationa
l use
historical data
and weather forecast
By 01.01.2011 – online estimation of
demand for each 15 min block
41
Demand Management(5.4)
• SLDCs shall control demand in the event of:
• insufficient generating capacity/inadequate external transfer
• breakdown/congestion problems
•
Demand disconnection
– frequency:
• below 49.7 Hz: shall initiate action to restrict their net drawal
• below 49.5 Hz: requisite load shedding
– Each User/STU/SLDC shall formulate contingency procedures and
make arrangements. Contingency Procedure to be regularly
updated and monitored by SLDC/RLDC
– SLDC through respective SEBs/Discoms shall formulate and
implement state-of-the-art demand management schemesroatational load shedding/demand response (which may include
lower tariff for interruptible load) etc. SLDC to furnish periodic
report to CERC.
42
Demand Management(5.4.2(e)(f)(g)(h))
• Interruptible load in four groups:
•
•
•
•
Scheduled load shedding/power cuts
Unscheduled load shedding
UFR/df/dt loads
SPS loads
• RLDC may direct to decrease drawal in contingency---SLDCto send
compliance report
• SLDC may direct SEB/Discom/bulk consumer to curtail drawal and
monitor
• RLDC shall devise standard, instantaneous, message formats
• Congestion – requisite load shedding or generation backing down .
Implementation as per CERC ( Measures to relieve congestion in real
time operation), Regulations, 2009
43
Periodic Reports (5.5)
• weekly report by NLDC (put on
website):
• weekly report by RLDC (put on
website):
– Performance of national/integrated
grid
– Frequency and voltage profiles
– Major generation & transmission
outages
– Transmission constraints
– Instances of persistent/significant
non-compliance of IEGC
– Instances of congestion
– Instance of inordinate delay in
restoration
– Non-compliance of instructions of
SLDCs by SEB/Discom
• daily report by RLDC (put on
website):
– Performance of national/integrated
grid
– Wind power injection
• quarterly report by RLDC :
– system constraints, reasons for not
meeting the requirements, security
standards & quality of service
– actions taken by different persons
– persons responsible for causing the
constraints
• RLDC shall provide
information/report to RPC for
smooth operation of ISTS
44
Operational Liaison (5.6)
• Introduction
a) requirements for the exchange of information in
relation to Operations/Events on the total grid system
which have had or will have an effect on:
• National grid
• the regional grid
• the ISTS in the region
• the system of a User/STU
(the above generally relates to notifying of what is expected to
happen or has happened and not the reasons why)
b) Operational liaison function is a mandatory built-in
hierarchical function of the NLDC/RLDC/SLDC/Users
to facilitate quick transfer of information to operational
staff
45
Procedure for Operational Liaison
• Procedure for Operational Liaison
a) Operations and event on the regional grid
• before carrying out any operation, RLDC will inform User/SLDC/CTU whose
system will be affected
• immediately following an event, RLDC will inform the User/SLDC/CTU with
details of what happened but not the reasons why
• RLDC to NLDC if other region is going to be affected
• immediately following an event, NLDC would keep all RLDCs informed
b) Operations and events on a User/STU system
• before carrying out any operation that will affect regional grid, constituent
shall inform RLDC with details
• RLDC to NLDC if other region is going to be affected
• immediately following an event, the User/SLDC shall inform RLDC with
details but not the reasons why
• immediately following an event, NLDC would keep all RLDCs informed
•
Prolonged Forced outages – monitored at RPC level. RPC shall send a
monthly report to CERC
46
Outage Planning (5.7)
Introduction
a) procedures for preparation of outage schedules for the
elements of the National/Regional in a coordinated and
optimal manner and the balance of generation and
demand
b) generation output and transmission system should be
adequate after taking outages into account to achieve
security standards
c) annual outage plan for the financial year shall be prepared
by RPC Secretariat and reviewed during the quaterly and
monthly basis. ROR, wind & solar power to be extracted to
maximum
47
Outage Planning Process
proposed outage programmes by all concerned (30th Nov)
draft outage programme by RPC Secretariat (31st Dec)
final outage programme by (31st Jan)
monthly review
Nov Dec
Jan
Feb
Mar
quarterly review
next financial year
Review by RPC Secretariat:
adjustments made wherever
found to be necessary in
coordination with all parties
concerned
48
Outage Planning (5.7.4)
• In consultation with NLDC/RLDC
• In Emergency – RLDCs may conduct studies before
clearance
• NLDC/RLDC are authorized to defer
- grid disturbance
- system isolation
- partial black out in a state
- any other critical event
• Latest detailed outage plan – updated
• Each user, CTU and STU shall obtain one final approval
from RLDC
• RPC shall submit quarterly, half yearly reports to CERC
indicating deviations
49
Recovery Procedures (5.8)
RLDC
develops
consultations
Concerned
Constituents
RPC secretariat
• Mock trials once
every 6 months
•DG sets to be tested
on weekly basisquarterly report to be
sent to RLDC
Detailed plans/procedures for
restoration of partial/total blackout
regional grid
reviewed/updated annually
develop
Detailed plans/procedures for
restoration of partial/total blackout
reviewed/updated annually
50
Recovery Procedures (contd...)
• List of the following shall be available with
NLDC/RLDC/SLDC:
–
–
–
–
generating stations with black start facility
inter-state/regional ties
synchronising points
essential loads to be restored on priority
• During restoration following blackout, RLDC
authorized to operate the grid with reduced
security standards for v & f
• all communications channels for restoration shall
be used for operational communications only till
grid normalcy is restored
51
Event Information (5.9)
• Introduction
– reporting procedures in respect of events to all Users,
STU,CTU RPC secretariat, NLDC/RLDC/ SLDC
• Responsibility
– RLDC/SLDC shall be responsible for reporting events
to the Users/SLDC/ STU/CTU RPC secretariat/ NLDC
/RLDC
– Users/ STU/CTU /SLDC shall be responsible for
collection and reporting all necessary data to
NLDC/RLDC and RPC secretariat for monitoring,
reporting, and event analysis
52
Reportable events (5.9.5)
i
ii
iii
iv
v
vi
vii
viii
ix
Violation of security Standards
Grid indiscipline
Non-Compliance of RLDC’s instruction
System islanding/ system split
Regional black out/partial system black
out
Protection failure
Power system instability
Tripping of any element
Sudden load Reduction
53
Reporting Procedure
NLDC
weekly written report
of events
RLDC
Users/STU/
CTU/SLDC
written report
of events
• Form of written reports:
i) Time and date
vi) Duration of interruption
ii) Location
vii) Recording System
informations
iii) Plant or equipment directly
involved
viii) Sequence of trippings with
time
iv) Description and cause of event
ix) Remedial Measures
54
v) Antecedent Condition
6. Scheduling & Despatch Code
a) demarcation of responsibilities
b) procedure for scheduling & despatch
c) Reactive power and voltage control
mechanism
d) complementary commercial mechanism
(Annexure-I)
55
OBJECTIVE
•Procedure for submission of Capability declaration
•Procedure for submission of requistion/ drawal schedule by regional entities
•Real time despatch/drawal instructions
•Rescheduling
• Commercial arrangement for UI/Reactive
• Scheduling of wind/solar on 3 hourly basis
•Appropriate Metering
SCOPE
Power
Exchanges
Discoms
NLDC
RLDC
SEBs/STUs
ISGS
SLDC
Other
concerned
Wind/Solar
generators
Demarcation of responsibilities (6.4)
Role of RLDC
Scheduling of CGS (Except where
full share is allocated to host state)
Scheduling
of GS
connected
both to
ISTS and
state grid
and home
state is less
then 50%
RLD
C
Schedul
ing of
GS
connect
ed to
ISTS
Scheduling of UMPP
57
Demarcation of responsibilities (6.4.4)
SLDC
Scheduling
drawal from
ISGS
Permitting
Open Access
Regulating
net drawal
6.4.8 Demand
Estimation in
coordination with
STU/Discoms
SLDC
Demand
Regulation
Scheduling and
despatching
58
Demarcation of responsibilities (6.4.6/7)
System of each regional entity shall be operated as
notional control area
Scheduled drawal +
Bilaterals on day
ahead basis
Regional entity would
regulate its own
generation and load so
that drawals are
close to schedules
Regional entity would Endeavour
for UI=0 at F<49.7 Hz.
At F< 49.5 Hz ,automatic demand
management scheme/manual
demand disconnection
59
Regional Entities Agreements
RLDC
State1 State2
State3
State4
RPC
Joint/bilateral agreements for
–State’s share in ISGS projects
–scheduled drawal pattern
–tariffs
–payment terms
State5
CTU
Long Term, MTOA
ISGS project1
ISGS project2
ISGS projet3
RLDC/SLDC
60
Declare DC
Faithfully
Penalty : Capacity
Charges reduced
6.4.9 Role of ISGS/
Generating Station
Planned Outages
OCC of RPC
When
F>50.2 ,
backdown
generation
Generate as per
despatch schedule
advised to them
by RLDC
DC during
Peak Hours
> Other
Hours
When F<49.7 ,
maximize generation
ISGS
Proper
Operation
and
Maintenance
Deviation
from
Schedule
UI
61
Role of CTU
Weekly
Readings
Constituents
where
SEMs
are
located
CTU
Install
SEMs
CEA (Installation and operation of
Meters ) Regulations 62
Demarcation of responsibilities
Role of RLDC
Periodically review UI
Report
MS RPC
RLD
C
15 min
drawal
and
injection
Gaming by ISGS
105 % in one block of 15 minutes and
101% over a day no gaming
63
Role of RPC
REA, UI,
Var
Accounting
RPC
Outage
Planning
64
Scheduling of
Inter-Regional
Power Exchanges
Trans-National
Exhange of
Power
Role of NLDC
HVDC
Settings
NLDC
Scheduling on
Inter Regional
Links .
Collective
Transaction
Scheduling
Energy
accounting
on IR Linkswith RLDC
65
Scheduling & Despatch Procedure (6.5)
•
List of ISGSs and beneficiaries
– all ISGS whose output is shared by more than state
shall be listed on RLDC and SLDC websites
– the station capacities and allocated/contracted shares
of different beneficiaries shall also be listed out
•
State’ entitlement:
– Thermal ISGS:
(foreseen ex-power plant MW capability for the day) X
(state’s share in the station’s capacity)
– Hydro ISGS:
(MWH generation capacity for the day) X
(state’s share in the station’s capacity)
66
Preparing final schedule
ISGS
station-wise
MW/MWH
capability
Despatch
schedule
final
Despatch
schedule
revision
Despatch
schedule
starts
RLDC
12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1
AM
noon
PM
station-wise W/MWH
entitlement
required
Drawal
schedule
net
Drawal
schedule
revision
final
Drawal
schedule
Drawal
schedule
starts
SLDC
67
Scheduling of Collective Transaction 6.5.5
Power
Exchanges
3. Check for Congestion
, reworked as per CERC
directive
1. List of
Interfaces,
Control areas
2. Interchanges on
Interfaces, Control
areas
NLDC
4.
Consultation
6.
Individual
Transactions
SLDC
7. Schedule
RLDC
individual
transaction
5.Schedule
at respective
periphery
68
Revision of schedules during the day
• any State may revise:
– drawal schedule from any/all ISGS within their entitlementsto be
effective from 6h time block)
• an ISGS may revise:
– capability on account of forced outage. (to be effective from 4th
time block)
– Revision (to be effective from 6h time block)
• RLDC can revise:
– In the interest of better system operation (to be effective from 4th
time block)
– Shall formulate procedure for meeting contingency
69
Other Contingencies
• In the event of bottleneck in evacuation of power,
RLDC may revise the schedules which will be
effective from 4th time block and for 1-3 time
blocks schedules would deemed to have been
replaced by actual.
• Similarly for entire period of grid disturbance,
schedules will be replaced by actual
• No revision – if change in previous
schedule/capability is less than 2%.
70
Other Contingencies
• For every change in generation schedule there
would be corresponding change in drawal schedule
• Procedure for recording the communication
regarding changes in schedules taking into account
to be developed by CTU
71
Final schedule & Documentation
• RLDC’s final implemented schedule:
– shall be the datum for commercial accounting
– shall be open for 5 days for verification/correction
• RLDC shall properly document the following:
– station-wise foreseen ex-power plant capabilities
advised by the generating stations
– the drawal schedules advised by beneficiaries
– all schedules issued by RLDC
– all revisions/updating of the schedules
72
Reactive Power & Voltage Control (6.6)
• VAR Charges under Low
Voltage
• VAR Charges under High
voltage
EHV grid
Q Voltage: < 97%
Beneficiary1
EHV grid
Q
Beneficiary2
VAR charges
Pool Account
Q Voltage: > 103%
Beneficiary1
Q
Beneficiary2
VAR charges
Pool Account
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VAR charges settlement
• No VAR charges for its own lines emanating directly from ISGS
• VAR charges at the nominal paise/KVArh rate as may be specified by
CERC and will be between beneficiaries and POOL (Present rate is
10.0 p/kvarh with escalation of 0.5 p/kvarh every year)
• RLDC may direct Regional entity to curtail VAR drawal/injection for
safety and security of grid or safety of equipment
• Beneficiaries to minimise injection/drawal of VAR if voltage goes
beyond + 5%.
• ICT taps may changed as per regional entity request to RLDC
• Tap changing (400/220 kV)and switching in/out of line reactors
(400kV) shall be carried out as per RLDC instruction.
74
Annexure-1 (6.1 d)
Complementary Commercial Mechanisms
75
Generation Cost
Capacity charge + Energy charge
beneficiary1
UI
UI
UI
Settlement
System
UI
beneficiary2
Capacity charge + Energy charge
ISGS
Full
reimbursement
for generation as
per the
generation
schedule
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Weekly bills & penalty (12, 13, 14)
UI bills
RLDC
RPC
UI payment
UI
Settlement
System
VAR payment
Pool
Account
Constituents
VAR bills
monthly payment
status
payment defaults
CERC
• payment within 10 days from date of billing
• simple interest @ 0.04% per day to constituent for delayed payment
beyond 12 days.
77
Regional Energy Accounting
15-minute block
SEM readings for a week
ISTS
Connections
Constituents
REA

Weekly raw
SEM data
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Mon
Tue
Weekly
Wed
UI and
Thu
VAR
Fri
Account
Sat
Sun
Mon
Tue
Monthly (6th):

RLDC
RLDC to tabulate UI account and REA in RPC’s CC
meeting on a quarterrly basis for audit by the later.
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Complementary Commercial
Mechanism
• Money left in VAR account shall be utilized
for training of SLDC operators and other
similar purposes
Thank you!